Tensioning a longwall mineral mining installation

Abstract

Mining apparatus comprises a longwall conveyor and tensioning means for tensioning the conveyor in its longitudinal direction. The tensioning means is constituted by a plurality of hydraulic tensioning rams, each of which is mounted, in use, by means of pivot joints at each end thereof directly between the conveyor and a respective roof support unit of a roof support assembly. Each tensioning ram extends at an acute angle to the longitudinal axis of the conveyor. The tensioning rams are positioned in two groups, one in each end zone of the conveyor.

We claim: 
     
       1. A mining apparatus, comprising: (a) a longitudinally oriented longwall mineral mining installation,   (b) a longitudinally oriented roof support assembly disposed adjacent and generally parallel to said installation, said roof support assembly comprising a plurality of roof support units,   (c) means for longitudinally tensioning the installation comprising two groups of hydraulic tensioning rams, each group being disposed at a respective end zone of the installation, and   (d) a plurality of attachment joints individually mounting the ends of each hydraulic tensioning ram directly between the installation and a respective roof support unit with each ram lying at an acute angle to the longitudinal axis of the installation, whereby the selected and controlled extension of the rams serves to longitudinally tension the installation.   
     
     
       2. Apparatus according to claim 1, wherein each of the attachment joints of each tensioning ram is a pivot joint. 
     
     
       3. Apparatus according to claim 1, wherein each tensioning ram lies substantially parallel to the other tensioning rams in that group. 
     
     
       4. Apparatus according to claim 3, wherein the axis of each tensioning ram points towards the adjacent end of the installation. 
     
     
       5. Apparatus according to claim 1, wherein the tensioning rams of each group are so positioned that the axes of each pair of adjacent tensioning rams are directed one towards and one away from the adjacent end of the installation. 
     
     
       6. Apparatus according to claim 3 or 5, wherein the installation is a longwall conveyor constituted by a plurality of channel sections joined end-to-end. 
     
     
       7. Apparatus according to claim 6, wherein each tensioning ram is attached to a respective conveyor channel section. 
     
     
       8. Apparatus according to claim 6, wherein a pair of adjacent tensioning rams are attached to each end channel section of the conveyor. 
     
     
       9. Apparatus according to claim 6, wherein each tensioning ram adjacent to an end of the conveyor has a longer working stroke than the other tensioning rams in that group. 
     
     
       10. Apparatus according to claim 9, wherein each of the longer working stroke tensioning rams is attached to a connector channel section which, connects the conveyor to a drive station. 
     
     
       11. Apparatus according to claim 7, further comprising a roof support assembly constituted by a plurality of roof support units positioned side-by-side of the goaf side of the conveyor, the units at the ends of the assembly being attached to the tensioning rams. 
     
     
       12. Apparatus according to claim 11, wherein each pair of adjacent tensioning rams are attached to a respective roof support unit. 
     
     
       13. Apparatus according to claim 12, wherein each roof support unit has a floor sill constituted by two spaced floor girders. 
     
     
       14. Apparatus according to claim 13, wherein the pair of tensioning rams associated with a given roof support unit are attached one of each floor girder. 
     
     
       15. Apparatus according to claim 14, wherein the tensioning rams associated with a given roof support unit converge from that unit towards the conveyor. 
     
     
       16. Apparatus according to claim 14, wherein the tensioning rams associated with a given roof support unit diverge from that unit towards the conveyor. 
     
     
       17. Apparatus according to claim 11, wherein each roof support unit is provided with a double-acting hydraulic advance ram coupled to the installation for advancing the installation in a direction at right-angles to its longitudinal axis, and for advancing that unit in a follow-up sequence. 
     
     
       18. Apparatus according to claim 1, further comprising control means for automatically relieving the tensioning rams as the associated roof support units are advanced in a direction at right-angles to the longitudinal axis of the installation. 
     
     
       19. Apparatus according to claim 18, wherein the control means is constituted by a plurality of control devices each of which is associated with a respective tensioning ram, and each of which has a check valve for relieving the associated tensioning ram. 
     
     
       20. Apparatus according to claim 14, further comprising a servo-piston for operating each check valve upon initiation of advance movement of the associated roof support unit. 
     
     
       21. Apparatus according to claim 20, further comprising means for actuating each servo-piston in dependence upon the pressurisation of a hydraulic advance ram of the associated roof support unit. 
     
     
       22. Apparatus according to claim 20, further comprising means for actuating each servo-piston in dependence upon the depressurisation of hydraulic roof support props of the associated roof support unit. 
     
     
       23. Apparatus according to claim 19, wherein each control device is provided with a control valve having three operating positions, in a first of which the associated tensioning ram is pressurised in a direction tending to extend that ram, in a second of which that ram is pressurised in a direction tending to retract that ram, and in the third of which that ram is isolated from pressurisation in either direction. 
     
     
       24. Apparatus according to claim 23, wherein each control valve is a manually operable spool valve. 
     
     
       25. Apparatus according to claim 1, wherein each tensioning ram is pressurised by means of a metering device. 
     
     
       26. Apparatus according to claim 25, wherein a respective metering device is provided for each group of tensioning rams. 
     
     
       27. Apparatus according to claim 1, further comprising variable pressure-reducing means for varying the pressure of the hydraulic fluid applied to the tensioning rams. 
     
     
       28. Apparatus according to claim 27, wherein the pressure-reducing means is constituted by a pair of variable pressure-reducing valve, each of which is associated with a respective group of tensioning rams. 
     
     
       29. Mining apparatus for use in a longwall working, the apparatus comprising: a longitudinally oriented longwall conveyor including a plurality of channel sections joined end to end, a roof support assembly including a plurality of roof suport units positioned side-by-side along the goaf side of the conveyor, and tensioning means positioned in two groups, one in each end zone of the conveyor, for tensioning the conveyor in its longitudinal direction, said tensioning means comprising a plurality of hydraulic tensioning rams, a plurality of pivot joints individually mounting the ends of each ram directly between the conveyor and a respective roof support unit, the axes of the pivot joints extending substantially at right-angles to the floor of the working, and each tensioning ram extending at an acute angle to the longitudinal axis of the conveyor.